Mucosal delivery of vaccines has been underutilized because of the problems associated with effectively delivering the vaccine antigens to the mucosal surface and to the underlying mucosal lymphoid tissue. Since mucosal surfaces are the port of entry of the majority of the infectious agents (Sabin, A. B., Vaccination at the portal of entry of infectious agents. Dev Biol Stand 33:3-9, 1976) it is important to the health of an animal to have developed a strong protective antibody and cell-mediated immune response at the portal of entry. This is best done with an adjuvant and delivery system that targets vaccine antigens to either the mucous membranes of the oral cavity, gut, nose, rectum, or vagina. Because this is not commonly done with an injectable vaccine, it would be advantageous to have a vaccine adjuvant delivery composition that would adsorb the vaccine onto the mucosal surface, and then, following absorption, be brought in contact with mucosal-associated lymphoid tissue.
For example, oral administration of a vaccine against a gut pathogen may engender a stronger immune response against such pathogens by eliciting the production of secretory immunoglobulin A antibodies at the mucosal site. This happens when the vaccine is presented to the gut-associated lymphoid tissue (O'Hagen, D, Oral Delivery of Vaccines: Formulation and Clinical Pharmacokinetic Considerations 1992, Clin. Pharmacokinet. 22 (1): 1-10). Likewise, administration of vaccine against an upper respiratory pathogen may be most effective if delivered to the mucosal-associated lymphoid tissue in the oral cavity or nasal passages. Interestingly, administration of antigens induces a mucosal immune response not only at the site of antigen application, for example the oral mucosa, but also at other mucosal sites such as the nasal mucosal (Mestecky, J I, The Common Mucosal Immune System and Current Strategies for Induction of Immune Responses in External Secretions. J Clin Immunol. 7 (4): 265-76).
Vaccinating large numbers of animals, such as cattle, swine and poultry, is extremely labor intensive and expensive. Each individual animal has to be handled at the time of vaccination in order to inject the animal with the vaccine. Most often the vaccine must be administered to the animal at least twice, and sometimes three or more times. It would be advantageous in terms of time and expense if the vaccine could be administered, simultaneously, with feed or water to a large number of animals.
Another advantage of targeting the vaccine to mucosal surfaces is that the vaccine can stimulate a protective immune response in the presence of circulating antibody that interferes with parenterally injected vaccines (Periwal, S B, et. al., Orally administered microencapsulated reovirus can bypass suckled, neutralizing maternal antibody that inhibits active immunization of neonates. J Virol 1997 (April 71(4): 2844-50).
Adjuvant systems to enhance an animal's immune response to a vaccine antigen are well known in the art. Likewise, systems for the delivery of vaccine and drugs to mucosal surfaces are known in the art. Different methods have been described to protect the vaccine antigen and drugs from degradation by stomach acid and digestive enzymes and to adsorb the antigen to the mucosal surface. Often these adjuvants and delivery systems include mixing the antigen with one or more components.
Examples of prior art adjuvants include the following.
U.S. Pat. No. 4,917,892, Speaker et al, issued Apr. 17, 1990, describes a topical delivery system comprising a viscous carrier containing a dissolved or dispersed active agent and active agent microencapsulated within a semi permeable anisotropic salt film which is the emulsion reaction product of a) a partially lipophilic, partially hydrophilic, polyfunctional Lewis acid or salt thereof in aqueous medium, such as carboxymethylcellulose, an alkali metal salt of polyacrylic acid or cross linked polyacrylic acid/polyoxyethylene, with b) a Lewis base or salt thereof in a water-immiscible, slightly polar organic solvent for the base, such as benzalkonium chloride, and piperidine. U.S. Pat. No. 5,132,117, Speaker et al., issued Jul. 21, 1992, discloses a microcapsule with an aqueous core, capsular, ionic stabilized anisotropic Lewis salt membrane formed from the interfacial reaction product of an emulsion of an aqueous solution of a water-soluble, hydrophilic polymeric Lewis acid or salt thereof with a non-aqueous solution of a lipophilic Lewis base or salt thereof. The Lewis base may be stearylamine, piperidine, or benzalkonium chloride and the Lewis acid may be carboxymethylcellulose, polyacrylic acid, or polyacrylic acid/polyoxyethylene copolymer, for example.
U.S. Pat. No. 4,740,365, Yukimatsu et al., issued Apr. 26, 1988 describes a sustained-release preparation applicable to mucous membranes in the oral cavity. The preparation consists of an active ingredient in a mixture of a polymer component (A) comprising one or more polymers selected from polyvinylpyrrolidone, polyvinyl alcohol, polyethylene glycol, alginic acid or a salt thereof, and an alternating copolymer of maleic anhydride and methyl vinyl ether and a polymer component (B) comprising one or more polymers selected from polyacrylic acid and a salt thereof. Polymer component (A) and (B) are in a ratio of 95:5 to 5:95 by weight. The preparation is layered with the active ingredient and may have optional conventional carriers and additives.
U.S. Pat. No. 5,451,411, Gombotz et al., issued Sep. 19, 1995, describes a delivery system for a cationic therapeutic agent whereupon alginate has been cross-linked in the presence of the therapeutic agent and polyacrylic acid to obtain a sustained release composition for oral delivery.
U.S. Pat. No. 5,352,448, Bowersock et al., issued Oct. 4, 1994, describes an oral vaccine formulation comprising an enzymatically degradable antigen in a hydrogel matrix for stimulation of an immune response in gut-associated lymphoid tissues. The hydrogel pellets are preferably synthesized by polymerizing methacrylic acid, in the presence of methylene bis-acrylamide and ammonium persulfate and sodium bisulfite.
U.S. Pat. No. 5,674,495, Bowersock et al., issued Oct. 7, 1997, describes a vaccine composition for oral administration comprising an alginate gel in the form of discrete particles. The alginate gel may contain a polymer coating such a poly-l-lysine to enhance stability and to add a positive charge to the surface.
U.S. Pat. No. 4,944,942, Brown et al., issued Jul. 31, 1990, describes an intranasal vaccine for horses, which may comprise polyacrylic acid cross linked polyallyl sucrose, sold as Carbopol 934P, combined with polyoxyethylene sorbitan mono-oleate and sorbitan monolaurate, preferably at 7.5 to 15 volume percent based on the total volume of the formulation, as an adjuvant.
U.S. Pat. No. 5,500,161, Andrianov et al., issued Mar. 19, 1996, describes a method for the preparation of microparticles, and the product thereof, that includes dispersing a substantially water insoluble non-ionic or ionic polymer in a aqueous solution in which the substance to be delivered is also dissolved, dispersed or suspended, and then coagulating the polymer together with the substance by impact forces to form a microparticle. Alternatively, the microparticle is formed by coagulation of an aqueous polymeric dispersion through the use of electrolytes, pH changes, organic solvents in low concentrations, or temperature changes to form polymer matrices encapsulating biological materials.
U.S. Pat. No. 6,015,576, See et al., issued Jan. 18, 2000, describes a method that comprises orally administering lyophilized multilamellar liposomes containing the antigen wherein the liposome preparation is contained in a pill form or within an enterically coated capsule. Such an enteric coating may be composed of acrylic polymers and copolymers.
U.S. Pat. No. 5,811,128, Tice et al., issued Sep. 22, 1998, describes a method, and compositions for delivering a bioactive agent to an animal entailing the steps of encapsulating effective amounts of the agent in a biocompatible excipient to form microcapsules having a size less than approximately ten micrometers and administering effective amounts of the microcapsules to the animal. A pulsatile response is obtained, as well as mucosal and systemic immunity. The biocompatible excipient is selected from the group consisting of poly(DL-actide-co-glycolide), poly(lactide), poly(glycolide), copolyoxalates, polycaprolactone, polyorthoesters and poly(beta-hydroxybutyric acid), polyanhydrides and mixtures thereof.
U.S. Pat. No. 5,565,209, Rijke, issued Oct. 15, 1996, describes oil-free vaccines comprising polyoxypropylene-polyoxyethylene polyols and an acrylic acid polymer as adjuvant constituents for injectable vaccines.
U.S. Pat. No. 5,084,269, Kullenberg, issued Jan. 28, 1992, describes an adjuvant, comprised of lecithin in combination with a carrier which may be selected from the group consisting of non-edible oil such as mineral oil and edible triglyceride oils such as soybean oil, for an injectable vaccine.
U.S. Pat. No. 5,026,543, Rijke, issued Jun. 25, 1991, discloses oil-free vaccines which contain polyoxypropylene-polyoxyethylene polyols as well as an acrylic acid polymer as adjuvanting constituents.
U.S. Pat. No. 5,451,411, Gombotz et al, issued Sep. 19, 1995, discloses alginate beads as a site specific oral delivery system for cationic therapeutic agents designed to target the agents to the luminal side of the small intestine. Enhanced bioactivity of therapeutic agents released from the alginate is attributed to the ability of polyacrylic acid to shield the agents from interaction with lower molecular weight fragments of acid treated alginate.
U.S. Pat. No. 5,567,433, Collins, issued Oct. 22, 1996, discloses a method of producing liposomes useful for encapsulating and delivering a wide variety of biologically active materials. The method involves the formation of a liposome dispersion in the absence of an organic solvent or detergent, one or several cycles of freezing and thawing, and dehydration to form a lipid powder. The powder is hydrated in the presence of a biologically active material to encapsulate it in the liposomes.
U.S. Pat. No. 5,091,188, Haynes, issued Feb. 25, 1992, discloses water-insoluble drugs are rendered injectable by formulation as aqueous suspensions of phospholipid-coated microcrystals.
The current invention relieves the problems found in the prior art by providing a simpler composition and easier method of formulation as well as providing easier delivery.
It is therefore a primary object of the present invention to provide a novel vaccine delivery system and adjuvant.
It is another object of the present invention to provide a vaccine adjuvant which is especially useful for mucosal delivery of vaccines.
It is a further object of the'present invention to provide a vaccine adjuvant that allows vaccine to be administered in animals' feed or water.
It is yet a further object of the present invention to provide a vaccine adjuvant that may be conveniently administered, practically simultaneously, to a large number of animals.
It is still a further object of the present invention to provide a method of incorporating antigen into a vaccine delivery system with minimal damage to vaccine epitopes.
It is a further object of the present invention to provide a simple method and means of manufacturing a vaccine delivery system that does not require harsh conditions such as elevated temperatures or organic solvents or detergents.
These and other objects, features, and advantages will become apparent after review of the following description and claims of the invention which follow.